1. Field of the Invention
The present invention relates to a computer system equipped with a plurality of CPUs (Central Processing Units) and having an automatic degradation/initialization function.
2. Description of the Related Art
Degradation denotes an operation in which a faulty component is isolated from a system and the system is reconfigured into a lower capacity state, and initialization process denotes a sequence of operations required from power supply to a computer until the computer becomes ready for executing a program. The initialization process includes power supply to individual devices, designation of operating mode and system configuration, initialization of the computer internal state (states of control flip-flops, registers, main storage, buffer storage, etc.), and loading of microprogram and various tables. In large-scale computers, the initialization process is performed under the control of an SVP (Service Processor).
In a conventional mainframe equipped with a plurality of CPUs, when power is supplied to the system, the SVP performs an initial diagnosis on the individual devices of the mainframe, such as the CPUs. If fault in a CPU is detected as a result of the diagnosis, the SVP informs such fault to a monitoring center, operation of the mainframe is suspended, and the initialization of an OS (Operating System) by IPL (Initial Program Loading), which should originally be executed thereafter if the system is normal, is prohibited.
However, some of various tasks (applications programs) executed by the mainframe do not require all CPUs to be operated and can be adequately accomplished with some remaining CPUs. Accordingly, there has been a demand for executing such tasks by isolating faulty CPUs and initializing the OS by the remaining CPUs.
The SVP has a function of isolating only faulty CPUs and initializing the remaining CPUs. Thus, the aforementioned demand may be met by using this function, but still remains unfulfilled because the number of CPUs required for executing each of the tasks is unknown.